Roller-grate stoker



April 27 1926.

- 1,582,303 J. w. PETTERD ROLLER GRATB STOKER Filed May 5. 1923 5 Sheets-Sheet 1 April .27 1926.

J. PETTERD ROLLER GRATE STOKER Filed May 5, 1923 3' Sheets-Sheet 2 April 27 ,1926.

J. W. PETTERD ROLLER GRATE STOKER Filed May 5, 1923 3 sheets-sheet 5 Patented Apr. 27, 1926.

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' Application filed May 5, 192 Serial it) seems.

Togzll whom'ifmay concern: J

Be It? known that 1, JAMES NVinLL-mr Purrnnn, a subyect of the King of Great Britain and Ireland, and residing at 118.

Bainbr'a Road, in the city of Caulfield, in the county of Bourke, State f Victoria, Commo-nw alth of Australia have invented certain new and useful Improvements in a ROlIer -Grate Stoker, of which the following-is a specification; p

This invention relates to relatively fixed rotating roller grate stokers and has for its objects to provide lDIPIOVQCllHBZlIlS for driv ing said rollers; to provide asimpleinexpensive construction whereby an auxiliarycur-rent' of air may be allowed to enter the fire chamber over the fire in starting up the fire or at suchother times as may seenradtionally rotate a series of fuelaconveyiiig rollers; which are omitted from; this view; Figure 4' is" apart sectional diagrammatic view of the fu'el conveying rollers and the friction rollers driving the. same. i s Figure is aplanof the fuel conveying Figure 6is' a sectional view'of a' fuel conveying ring, or roller section. I

Figure 7 is a side elevation; and y Figure 8 an edge elevation of a fuel con veying ring or roller section: r

Tlie'invention includes a series of driv- 1g rollers 2 mounted upon transverse shafts 3 and rotated by Worm gear 4 or the like from a longitudinal driving shaft or shafts 5. The shaft 5 maybe provided with a speed cone 6and be rotated through any suitable gearing. The shafts are mounted in any suitablebearings. i The rollers 2 may be either plain or corrugated and their'position in relation to each other may be varied from that shown. The rollers may be built up bya number of rings or sections placed upon and spaced apart upon theshafts 3 if desired. They'all rotate inthe same direction l Resting upon the driving rollers '2 and frictionally rotated thereby is a series of fuel conveying rollers. These are preferably corrugated and inay be built up'upon transverse shafts 7 by rings or sections 8,

or the like, suitably spaced apart, if desired. By building up the rollers S with rings or sections the width of. the furace may be readily accomn'iodated; The corrugated fOllIllitlGn' also provides an increased grate area. The roliers 8, further, may ,be'rotated or driven direct or positively instead of frictionally if desired. Each lroller sec 'tion 8 maybe hollow and have formedtherein a series of 'air spaces indicated at 9 Wherebythe .air supply passin between the rollers 2 passes to the fuel through the rollers supportingit and is heated in transit. From Figures 6; 7 andS it will be seen that the corrugation orperiphery of 'each section 8 is united by spokes 10 to a divided boss 11 having incuts or recesses 1-2.- {Each section therefore only bearsupon its=shaft- 7 at the corners 13. Divisionof the boss and the provision of the recesses 12 and th e general construction of the roller sections provide for lateral expansion underthe heat of the 1 furnace; The shafts 7 need not necessarily be of square or similar conformation. And obviously 'tlie'roller sections need nt be provided Withspecific spokes.

The air spaces or openings 9 in theroller sections 'may be of increased area in the rollers located at the middleof the furnace;

in order to provide or introduce agreate-r volume of air Where the fire 1S fiercest; Any

ell known ineans may be used to regulatethe delivery of air to any part=of the, grate such as dampers and a partitioned air boxor conduit,- dependent upon the furnace con; struction. The arrangenient of the roll'ers .2 and 8 may be such that those at the feed cndfof the furnace rotate at a faster speed than those at the delivery :or ejector end;

Under normal conditions the rollers located at or near the delivery end of the furnace grate'rotate at a slower speed than those situated at the receiving end and the mid die of the grate. The fire is more intense or is fiercest ator near the middle of'the furnace and the fuel may be passed through ter or disc operated by a hand knob 22. Any

more quickly or be provided with more air accordingly. The speed of the rollers may be varied through the mechanical agency by which they are rotated, according to circumstances, and with the object of maintaining an even thickness or layer of fuel during consumption.

Above the front or feed end of the stoker is a fuel hopper 1% or the like having a sliding control door 15 operated by worm or toothed gearing 16 and a handle 17 or the like. Located at the bottom of the hopper is a roller or rollers 18. This may be driven in any well known way or it may be separately or manually or otherwise rotated.

Adjacent the feed or supply roller 18 is a hinged flap 19 or the like to provide an'air supply for starting up the fire and admitting an auxiliary supply of air over the fire when necessary.

An indicator 20 may be used to show the position of the flap 19. The front of the furnace is also provided with a door 20 having inspection openings indicated at 21. These are closed by a. suitable rotary shutother suitable inspection means may be used.

Disposed at the rear end of the series of rollers 8 is an ejector 23. This may be built up laterally by a series of rings or sections to interengage with the end fuel carrying rollers. The ejector may comprise a plurality of pockets indicated at 24: between which are circumferential closing or roller engaging faces 25.

lVith this invention the fuel is positively fed from the hopper 1a to the rotating rollers 8 at the feed or front end of the furnace. The rollers 8 pass the bank of fuel into the furnace towards the rear thereof and over or upon succeeding rollers 8. The fuel bank spreads or thins outwardly as it moves onward and by the heat of the fur nae-e the particles cohere causing the mass torest upon crowns of the corrugations of the rollers 8 as it proceeds. It will be seen that the cor 'ugations of the rollers carried byeach shaft 7 alternate or interengage with those of the succeeding shaft. It will also be seen that air spaces or combustion chambers, indicated at 26, are formed below the fuel and in depressions between corrugations. Air entering between the dr'iv ing rollers 2 encounters the heated fuel carrying rollers 8 and passing therethrough is thoroughly heated before it enters the spaces 26 and encounters the fuel bridging the crowns of the corrugations. The air also serves to cool the rollers. Although the smaller particles of fuel matte or clinker under the influence of the heat the interengaging or staggered arrangement of the corrugated rollers is such that the fuel is sufficiently agitated or broken to ensure eliicient combustion. The heated air supply is direct. When the ejector is reached the fuel has been consumed and the ashes are delivered from the last group of rollers 8 into the pockets 24 of the rotating ejector. The circumferential faces 25 ensure that the ashes enter the pockets and are delivered therefrom where desired. A chain, screw or other conveyor of any suitable and known type may be provided beneath the rollers in some types of boilers, such as Cornish and marine types to receive the ashes and discharge them at the front of the boiler.

As beforementionod the basis of the invention is a series of rollers to deliver or carry the fuel through the furnace but substantial noveltyis believed to reside in the variation of the speed of the rollers to improve combustion and to more positively prevent matting of other than small particles of the fuel, and in variation of the air supply to ensure complete consumption.

I claim A roller grate stoker comprising a plurality of grate rolls relatively fixedly mounted with relation to each other, in combination with means for rotating said rolls, said means comprising a plurality of shafts arranged in a single plane and each provided adjacent its central portion with a small gear wheel, and adjacent each end with a larger drive wheel, whereby each shaft will carry driving means equally engaging with the ends of the grate rolls respectively, aid gear wheels of all said shafts being aligned in a direction transverse of said shafts, and a drive shaft carrying driving means intermeshing with said respective gears'to positively drive all of said shafts simultaneously.

In testimony whereof, I have signed my name to this specification.

JAMES TVILLIAM PETTERD. 

